Lesson video

Hi there.

Welcome to our lesson on comparing pie charts.

Our agenda for today is to analyse pie charts, to compare them, and then you'll do some independent learning, and a final quiz.

All you'll need is a pencil and piece of paper.

So pause the video and get your equipment if you haven't done so already.

Let's jump straight in and start looking at some pie charts.

So here we have a company called Striders that make crisps.

They asked 100 people their favourite flavour crisp, and they presented it in this pie chart.

So you can see that the pie chart has a key at the bottom to show what each segment represents.

What I would like you to think about, is what you can tell from this data.

What statements can you generate about this pie chart? Pause the video now and write some statements down.

So the first thing I notice, is that they survey people about five different flavours.

So we have got five segments in the pie chart.

They asked about one, two, three, four, five flavours, and that's reflected in the key.

The favourite flavour was salted.

We can see that this lighter red section is the largest proportion of the pie chart, which means that that was the overall favourite flavour.

And the least favourite flavour is pickled onion.

So this dark purple represents the smallest segment of the pie chart.

And I disagree with that, because I think pickled onion crisps are delicious.

Then we can also say that around a quarter of the people asked preferred cheese and onion.

So you can see this segment here.

This represents about a quarter of the pie chart.

And you can see if you look in the very corner of that segment, that's about a 90 degree angle.

We know that a whole pie chart is 360 degrees, and a quarter of 360 is 90 degrees.

So if that is a quarter of the people, we know that 100 people were asked, that would mean that 25% chose cheese and onion.

So now you have two pie charts to compare.

So we've got a rival crisp company called Hikers, and they surveyed 160 people, and they presented their results in this pie chart.

So we've got our original one and our new one.

I want you to have a think about what is the same and what is different about these two pie charts.

Pause the video now and make some notes.

So what I noticed was, the first thing is that they surveyed a different number of people.

So Striders only surveyed 100 people, whereas Hikers surveyed 160 people.

The second thing is that we had five flavours surveyed for Striders.

And Hikers, they surveyed the same five flavours, but they also added on paprika.

So they actually surveyed six different flavours.

And we can see that while Striders least favourite flavour was pickled onion, Hikers, their least favourite flavour is paprika because you can see it's the smallest segment.

The other thing that I noticed was that the proportion of people that chose cheese and onion is the same.

But does that mean that the same number of people chose cheese and onion for each company? So remember, we said it was about a quarter.

We can't be accurate, but we can just say it was roughly a quarter.

So that will be 25 people from the Striders.

But a quarter of people from Hikers is actually more.

A quarter of 160 will be 40 people.

So, what's very important is that although this looks like the same amount, it's the number of people surveyed or the number of things that the pie chart is about.

That is the most important thing to focus in on.

So let's have a look at a different pie chart.

So here we have two pie charts that show people's favourite fruits.

And you can see that they're surveying six, while five fruits and one which is just an other category.

So the orange one is any other fruit other than the five that they've asked about.

And Arran says that the pie chart on the left is larger.

So therefore it must represent more people.

Is Arran correct? So, Arran is not correct because it is not about the size of the pie chart, it is about the number of people surveyed.

We have to be given that information in order to apply that to the pie chart.

So he's not correct in his conjecture here.

So remember that the most important thing is knowing how many people or how many things the pie chart is about.

So here we have a pie chart where we are given that information.

So the first one has surveyed 80 people and then the second one 300 people, but they're being asked the same questions.

So Wendy says that more people chose apples in the first survey than the second survey.

Is she right? So have a look, the apple section is purple.

It's the same size, the same proportion in each pie chart.

In which one did more people choose apples? Pause the video now and do some working out.

So what we can see is that less people were surveyed in the first pie chart than the second which means that this segment here represents less people.

And we can take it a little bit further.

We can see that these two segments next to each other represent apples and oranges.

You can see the apples are purple.

The oranges are light blue.

And that represents around a quarter of the whole pie chart.

And actually, this apple section is a half of this together, which means that the apple section represents about an eighth.

So that would be an eighth of 80 people would be eight people.

And then we can think about the same for the 300 people.

Again, this is representing an eighth of the whole number of people.

And we can say that an eighth of 300 by dividing 300 by eight is around 37 people.

So we can see that it's more in the second pie chart.

Now it's time for you to do some independent learning.

So pause the video now and complete the tasks and then click Restart once you're finished so that we can go through the answers together.

So you were given some pie charts, where Fin and Sally observed animals in Richmond park at night.

So the first thing to do when you're presented with a pie chart, it's just to get a really good overview of what you're being shown.

So we know Sally saw 70 animals, Fin saw 160 animals.

We can see that half of the animals that Sally saw were foxes.

And we can see that a quarter of the animals that Fin saw were foxes, the purple ones.

But they saw different numbers of animals so that will represent a different amount of foxes for each of them.

And we can also see quite clearly on Fin's pie chart, that around a third of the animals he saw were mice, and about a third were owl and deer.

And actually, that's roughly half of a third each, which means that a sixth of the animals that Fin saw were deer.

So let's go through the questions that you were asked.

So the first one was about how many foxes they saw.

So we said 50% of the animals Sally saw were foxes.

50% of 70 is 35.

And for Fin that represented about 25%, and 25% of 160 animals is 40.

So Fin saw more foxes than Sally, despite her fox segment being much bigger than Fin's.

I used percentages here, but you may have used fractions of the pie chart as well, which will just work exactly the same way.

The second question was about mice.

So we could see that just under a quarter or just under 25% of Sally's animals were mice.

We can see that 25% of 70 is 17.

5.

Well, you can't see half a mouse.

So I've rounded that up to 18.

But remember that without being given any more specific information, for example, being given angles of each segment, we're unable to be completely accurate.

So we're saying approximately 18 mice.

So there we know it's slightly less than that.

And for Fin, we said it was a third of the animals that he saw.

A third of 160 is 53.

3.

Again, you can't see a third of a mouse, so I have rounded that down to 53 as an approximation.

And then finally, we're talking about owl and deer.

So we can say that approximately a third of the animals that Fin saw were owl or deer.

And we said that a third of 160 was approximately equal to 53.

Excellent work today.

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